Signaling by electromagnetic waves.



9. A. PBSSBNDBN. SIGNALING BY AELECTROMAGVNETIG WAVES. `APPLICATIONFILED MAY 4, 1906.

PatenaJulyzo, 1909.

WITNESSE'S:

REGINALD A. FESSENDEN, OF WASHIGTON, DISTRIGTVOF COLUMBIA.

sIGNALrG BY ELECTROMAGNETIC wA'vEsL Specification. of Letters Pate-nt.

Patented July 2o, i909.

Application nled Hay 4,y 1966. Serial No. 315,266.

,To all whom fit may concern:

Be it known `that I, REGINALDfA. FEssEN- DEN, a citizen of the UnitedStates, residing at Washington, District of Columbia, have inventedcertain new and useful Impovements in Signaling by ElectromagneticWaves, of which the following is a specification. i

. M` invention herein relates generally to wire ess telegraphy, and moreespecially to provision for tuning the circuits in apparatus for thispurpose, as hereinafter more fully described. I

In the accompanying drawing forming a art of this specification, Figures1, 2 and 3 illustrate diagrammatically different combinations ofelements of my improved apparatus, and Figs. 4 and 5 show in plan andsection a variable transformer.

, In the practice of my invention, I provide a capacity and inductancein shunt to each other and in operative relation to the aerial, and areceiver in operative relation to the condenser and inductance circuit.

The aerial 1 isgroundedas at 2, and has a variable inductance 3 inseries therewith. The aerialFig. 1 is also connected to inductances 4and 6, in shunt to a condenser 5.

The inductance 4 is preferably variable and the inductance 6 forms ltheprimary of a transformer. having a secondary 7. Both 6 and 7 arepreferably constructed so as to be capableof yadjustment as illustratedin Fig. 4. A rcceiver'8, telephone 9, potentiometer -10, inductance 11and condenser 12 are arranged in the circuit of the secondary 7. Thecondensers 5 and 12 are preferably adjustable, as is also the indutance11. The aerial is preferably tuned to the frequency of oscillationswhich it is desired to receive, and also the shunt circuit 4, 5 and 6,either alone or in conjunction with the secondary circuit 7, 12, 8 and11. The circuit 7, 12, 8 and 11 is also preferably tuned to thefrequency which it is desired to receive.

In the construction shown in Fig. 2, the aerial 1, which is grounded asat 2, is connected in series with the inductance y14. The inductances 15and 16, which are preferably adjustable, are shunted by the variablecondenser 13. The receiver 19 is connected across the inductance 16. Theycircuit of the receiver 19 includes a variable inductance 18, anadjustable capacity 17', telephone 20, and

potentiometer 21,. 'Contact points c and b.

are adjustable.

The construction shown in Fig. 3 is especially applicable for use forthe prevention of interference. The aerial 1 is grounded as at 2 and isconnected tothe variable inductances 3, 24 and 25. The aerial is alsoconnected to inductances 27 and 28, whichfare arranged in shunt to thecapacities"l or condensers 23 and 26. The inductances 27 and 28 formprimaries whose secondaries are shown at 29 'and 30. In the circuit withthese secondaries are included the variable inductance 31, adjustablecapacity 36, 'receiver 34, 'potentiometer 35 and telephone or otherindicating instrument 33.` The transformers have preferably a variable.ratio of turns, the construction shown in Fig.

quency, and the circuit 1, 3, 25, 26, 28 and 2i to the other frequency.

The variable transformer shown in Figs.

v4 and 5 consists of two pairs of drums 37, 38,

and 39, 40,-of which the drums 37 and 40 are referably formed ofmetal'or other conductlng material, andy are mounted in suitablebearings so as to be capable of rot-ation, while Where, e

the drums 38 and 39 are formed of insulating p v material, the drum 39being rotatable within the' drum 38 and adjustable in and out of thesame by means of the threaded rod 41 passing through drum or cylinder39. The drums 37 and 38 are made of the same diameter and are adapted tobe driven simultaneously by suitable connection, as, for example, thesprocket chain 42;, shown. and ,40 are also of the same diameter and areconnected by a s rocket chain 43 .or other suitable means. v

alsoy adjustable longitudinally by means of a screw 44. A. portion of alength .of wire is wound on the drum 37, and another portion on the drum38, and by rotating these drums,y

The drums 39 he drum orcylinder 40 is v is wound artially on the drum 39and )artially on t e drum 40, and by rotating t fese drumsthewire can bewound oli of one and on to the other. It will be observed that as thewire is wound off or on the drum 39, it is moved 'axially out of andinto the drum 38,

'and that the coils on the drums 38 'and 39 will form the members of atransformer which canbe varied by rotating these drums in the mannerstated.

I am aware that the use of a shunt resonant circuit for producingselectivity in electro-magnetic apparatus is old. VI am also aware thatthe use of a secondary operatively connected to an inductance` inparallel with a' condenser is old, where the short circuited coil of ashort circuitcd dynamometer operates as a secondary. And I am also awarethat this arrangement has been used in connection with an untunedaerial.

The interference,preventer may be used.

with four branch circuits, with a sending station emitting twofrequencies in this case, two of the branches are rei'erably tuned tothe two frequencies' whic it is desired to receive, and the otherbranches are used as balancing branches to cut out interfering signals.

I claim herein as my invention:

1. In a receiving system for Wireless teleg` raphy, an inductiveconnection with variab e primary, a condenser, a detectoriorelectroy'magnetic waves connected with the secondary of the inductiveconnection through said condenser, a condenser shunted with the lowresistance for electric oscillations, an antenna, connections from saidloop to the antenna and to the ground.

3. In asystem for wireless telegra hy an' inductive connection having avaria le primary, a detector for electromagnetic waves in circuit withthe secondary of said inductive connection,an antenna in circuit withthe primary of said inductive connection through a variable inductance,and a condenser shunted about the variable primary.

4. In a receiving system for wireless telegraphy a circuit including acondenser and 'a detector for electromagnetic waves, a circuit.

including an elevated conductor and a variable inductance, and aninductive connection between said circuits having a primary, variable asto the number of its turns, in series with the variable inductance andelevated conductor. y

5. In a receiving system for wireless telegraphy a circuit including acondenser and a detector for electromagnetic waves, a circuit lincluding an elevated conductor and a variable inductance andaninductive connection between said circuits havingv a primary in serieswith the variable inductance and elevated conductor and having asecondary variable as to the number of its turns in series with'thecondenser and detector.

6. In a receiving system for wireless telegraphy an inductive connectionhaving a primary and secondary variable as to the ratio of their turns,a detector for electromagnetic waves in circuit with the secondary, andan elevated conductor in circuit with the primary through a variableinductance.

In testimony whereof, Iliave hereunto` set my hand. v

REGINALD A. FESSENDEN.

l Witnesses:

LEONARD MORGAN, WILLiAM HELGEN.

